| In lives of modern society, people usually spend about 80%~90% time in interior, so the indoor air quality has very big effect in work and live of people. Nevertheless, the domestic and international investigation indicates that there are serious problems relatively existing in numerous buildings' indoor air quality. To this point, the research of indoor air quality has already become the forward subject in modern architecture and air conditioning engineering. It involves in medical health, the architectural environment engineering and architectural design, etc. By this study, a healthy and comfortable indoor environment will be created. So, it is very important to carry on indoor air quality study.Firstly, the development of this research have been introduced in this paper, then a set of general mathematical models for the VOC emission from furnishing materials was constructed and definitions and arithmetics of the influential factors were explained. According to the mathematical model,a simulation method was created by uniting mathemical simulation with CFD.Therefore, the formaldehyde as an example of VOCs could be simulated on a real room in consideration of all factors.The simulation method could be considered reliable because of fitness of the simulation values and the testing ones by contrast them.In the simulation process of this paper, a model of rooms should be constructed firstly, and the average air flow rates on floor surface could be calculated out by CFD secondly. Therefore the average convective mass transfer coefficients of formaldehyde could be obtained. Then formulas of emission by programming and curve fitting could be used by UDF(User Defined Formula) into CFD simulation, so the formaldehyde concentration field could be shown. Because the mathemical simulation is on the premise that the concentration field was homogeneous, there must be deviations. Therefore the average concentration values could be corrected by CFD results and the simulation process was predigested. In the last,the standard reaching process could be simulated using this method, and the time which was needed by standard reaching under normal ventilation could be calculted out. According to the simulation result of VOC emission from floors,it's known that it was relevant to many factors. From the beginning, the VOC emission rates and the formaldehyde concentration in the air decayed very rapidly and stabilized after tens of hours.At the same time, the speed of decreasing in concentration in the supercrust of floor is so obvious, but the concentrations in deep was almost unchanged. Therefore, given that ventilation was stopped for a moment,the emission rate and concentration in the air would return to high standard. There were also difference in decreasing rate in rooms which were different in ventilation, so better ventilation, more obviously emission process decayed. For parts of a room,it was also differcent in concentration because of the different ventilation degrees. In a word, reinforce the ventilation was the most simple and reasonable method to solve the problems of IAQ.In despite of some limiations in the simulation method in this paper, it was so liable that it can unit all factors to draw out the concentration fields. So, the simulation method is better applied in the subject which was about the control of VOC in home-fitment. |
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